Dual-catalyst hydrofining process

ABSTRACT

A hydrofining process to reduce the nitrogen content of mineral oil feedstocks at relatively high-space velocities which comprises contacting the feedstock and added hydrogen with a conventional, substantially nonzeolitic, amorphous-based hydrofining catalyst, and contacting the effluent therefrom with a second hydrofining catalyst comprising a hydrogenating metal or metal sulfide supported on an active zeolitic cracking base.

United States Patent Kelley et al.

[54] DUAL-CATALYST HYDROFINING 5] Feb. 22, 1972 3,338,8l9 8/1967 Wood ..208/97 PROCESS 3,140,253 7/1964 Plank et al. ,4 9 1 G ld [72] lnventors: Arnold E. Kelley, Orange; Frederick C. 3 37 58 4/ 969 o thwalt 208/254 wood Fullerton both of Cahf' Primary Examiner-Paul M. Coughlan, Jr. [73] Assignee: Union Oil Company of California, Los An- Assistant ExaminerG. J. Crasanakis geles, Calif. Attorney-Milton W. Lee, Richard C. Hartman, Lannas S. [22] Filed: Jam 31, 1969 {1233618011, Dean Sandford, Robert E. Strauss and Michael H.

[21] Appl. No.: 795,500

[57] ABSTRACT [52] US. Cl. ..208/89, 208/254 H A hydrofining process to reduce the nitrogen content of [51] Int. ..Cl0g 23/02 mineral oil f d t k at relatively high space velocities which [58] Field of Search ..208/89, 142, 254; 252/455, comprises contacting the f d k and added hydrogen with 252/455 Z a conventional, substantially nonzeolitic, amorphous-based hydrofining catalyst, and contacting the effluent therefrom [56] Rem-em Cited with a second hydrofining catalyst comprising a hydrogenating UNITED STATES PATENTS metal or metal sulfide supported on an active zeolitic cracking base. 2,967,159 1/1961 Glatirowet al "252/455 3,256,178 6/1966 Hass et a1 ..208/89 17 Claims, 1 Drawing Figure F550 sracx F PRODUCT 44 DUAL-CATALYST I-IYDROFINING PROCESS BACKGROUND AND SUMMARY OF THE INVENTION has a deleterious effect on hydrocracking catalysts and that.

removal of the organic nitrogen in the feedstock is a necessary step in most hydrocracking processes. It is also well known that lower hydrocracking temperatures can be employed and longer run lengths can be realized'in hydrocracking by reducing the nitrogen content of the feedstock to low levels, e.g., below 25 parts per million (p.p.m.) and preferably below p.p.m. Conventional hydrofining catalysts can reduce the nitrogen content of the feedstock to these low levels; however, uneconomically low space velocities, high pressures and/or high temperatures are required.

According to the present invention, it has been found that the organic nitrogen content of a feedstock can be reduced to low levels at relatively low temperatures and pressures and at relatively high space velocities by a dual-catalyst system wherein the feedstock in the presence of hydrogen is first contacted with a conventional, substantially nonzeolitic hydrofining catalyst and is then contacted with a zeolite-based hydrofining catalyst comprised of a hydrogenating metal and/or sulfide thereof supported on a zeolitic cracking base having a cracking activity greater than that corresponding to a Cat-A Activity Index of about 40. Heretofore, it was considered undesirable to hydrofine with catalysts having a cracking activity higher than that corresponding to an Activity Index of about 25. We have discovered that zeolite-based catalysts of high cracking activity can be advantageously employedwhen utilized in combination with a conventional nonzeolitic hydrofining catalyst.

The object of the invention, therefore, is to provide a method of reducing the nitrogen content of a hydrocracking feedstock. Another object of the invention is to reduce the nitrogen content of the feedstock to below 25 p.p.m. and preferably below 10 p.p.m. at relatively low temperatures and pressures, and at relatively high space velocities. A still further object of the invention is to reduce the nitrogen content of high-boiling feedstocks comprising highly resistant organic nitrogen compounds at relatively low temperatures and pressures and at relatively high space velocities.

These and other objects of the invention'will be-apparent from the detailed description of the process which follows.

DETAILED DESCRIPTION TABLE 1 Hydrofining Conditions Broad Range Preferred Range Temperature, F. 600-850 650-800 Pressure, p.s.i.g. 4004.000 SOD-2,500 LHSV. VIV-HR. 0.5-) 0.9-7 H,/uil ratio. MSCF/B ().5- 242 The above conditions are suitably adjusted so as to effect partial denitrogenation of the feedstock, the extent of which will be described hereinafter.

The partially hydrofined feedstock is passed from the conventional, nonzeolitic hydrofining catalyst A in hydrofiner 8 through the zeolite-based hydrofining catalyst B, to be described hereinafter, where hydrofining proceeds even further under substantially the same conditions as those tabulated above, said conditions being correlated to carry the denitrogenation to the desired degree of completion. And,"as will be discussed hereinafter, the space velocity over catalyst B is preferably higher than the space velocity over catalyst A. Due to 'the presence of substantial quantities of organic nitrogencompounds in the catalyst B zone, little or no cracking of hydrocarbon components occurs and conversion to low-boiling materials is insubstantial. Conversion to products (e,.g., gasoline) boiling below the initial boiling point of thefeed is normally less than about 25 volume-percent and preferably less than about 15 volume-percent and the dry-gas make" (i.e., C -C yield) is usually less than about 60 SCF/barrel of feed, preferably less than about 30 SCF/barrel.

At this point, if further hydrocracking is not desired, the effluent from hydrofiner 8 may be withdrawn, cooled and fractionated to separate desired denitrogenated products. However, in the modification illustrated, further hydrocracking is desired, and hence the total hydrofined product from hydrofiner 8, including ammonia and hydrogen sulfide formed therein, is withdrawn via line 10 and transferred via heat exchanger I2'to hydrocracker 14. Heat exchanger 12 is for the purposeof suitably adjusting the temperature of feed to the hydrocracking catalyst zone 15; this may require either cooling or heating, depending on the respective hydrofining and hydrocracking temperatures employed. The process conditions in hydrocracking zone 15 are suitably adjusted so as to provide about 20-70 percent conversion per pass to gasoline and/or other products, while at the same time permitting relatively long runs between regenerations, i.e., from about 2-12 months or more. For these purposes, it will be understood that pressures in the high range will normally be used in connection with temperatures in the high range, while the lower pressures will normally be used in conjunction with lower temperatures. The range of operative hydrocracking conditions is as follows:

TABLE 2 Hydrocracking Conditions Broad Range Preferred Range Temperature, F. 550-850 650-800 Pressure, p.s.i.g. 400-],000 $004,500 LHSV,V/V-HR 0.5-10 [-5 H,/oil ratio, MSCF/B 0.5-20 2 [2 It is important to observe that, if the hydrocracking catalyst is the same as the hydrofining catalystB, a substantially lower average bed temperature should be maintained in the hydrocracking zonethan in hydrofining catalyst bed B. This is to avoid overcracking which'would otherwise take place in the hydrocracking zone in the substantial absence of organic nitrogen compounds. Normally in such cases, the average bed temperature in the hydrocracking zone should be about l0-80 F., preferably 3070 F., lower than in hydrofining catalystbed B. This will normally require cooling of the bed B effluent-to below the inlet temperature of bed B.

Effluent from hydrocracking zone 15 is withdrawn via line I8 and partially cooled and condensedin'exchanger 20 to a temperature'of e.g., 200-400 F., and mixed'in line 22 with wash water injected via line 24. The resulting mixture is then further cooled in exchanger 26 to a temperature of e.g.,

5 2 0 0:F., and transferred into high-pressure separator 28, from which spent wash water containing dissolved ammonia and ammonium sulfide is withdrawn via line 30. Hydrogenrich recycle gas is withdrawn via line 32 and recycled to line 2 via line 4. The condensed liquid product passes via line 34 into low-pressure separator 36, from which light hydrocarbon gases are exhausted via line 38. Low-pressure liquid condensate is then transferred via line 40 to fractionating column 42, from which desired product, e.g., gasoline, is taken overhead via line 44, and unconverted oil boiling above about 350-400 F. is withdrawn as bottoms via line 46. This unconverted oil may be recycled to hydrocracking zone 15 for further conversion to gasoline, or sent to a second hydrocracking stage (not shown) operated substantially in the absence of ammonia, whereby hydrocracking may be carried out at substantially lower temperatures than in zone 15.

It should be understood that the above-described process flow is for purposes of illustration only and that other flow schemes may be employed using the novel features of the invention. For example, the effluent of hydrofiner 8 withdrawn via line 10 may be partially cooled and condensed and waterwashed to remove ammonia and ammonium sulfide, and the washed condensate may then be fed to hydrocracker 14. The hydrogen contained in the effluent from hydrofiner 8 may be separated from the condensate and recycled back to hydrofiner 8. Also, any low-boiling products (e.g., gasoline, jet fuel, and/or diesel fuel) in the effluent of hydrofiner 8 may be separated from the high-boiling fraction (e.g., gas oil) therein so that such low-boiling products are not subjected to hydrocracking conditions in hydrocracker 14. Additionally, hydrofining catalyst B may be located in the upper section of hydrocracker 14 in lieu of being located in the bottom section of hydrofiner 8, with the temperature of the feedstock and hydrogen entering the hydrocracking section of hydrocracker 14 being controlled by introducing quench hydrogen into the hydrocracking section. It is preferably, however, to locate hydrofining catalyst B in the bottom of hydrofiner 8 because it is usually more reliable and more efficient to control the temperature of the feed and hydrogen entering the hydrocracking section by heat exchanger 12 rather than by quench hydrogen.

As indicated hereinabove, the feedstock to hydrofining catalyst B is only partially hydrofined by the conventional, nonzeolitic hydrofining catalyst A, and the zeolitic hydrofining catalyst B completes the desired denitrogenation. The optimum amount of denitrogenation effected in each of the respective catalyst beds varies with the particular type of feedstock, tolerance of the hydrocracking catalyst to nitrogen poisoning, catalyst costs, vessel costs, and other similar factors. Generally, it is preferable to remove a substantial portion, e.g., 5099 percent, preferably 75-98 percent, of the organic nitrogen in the upper catalyst bed B and to utilize catalyst B to reduce the nitrogen content of the gas oil to the low level desired.

For example, with a feedstock containing about 2,0004,000 p.p.m. organic nitrogen and where it is desired to reduce the organic nitrogen content to below about 5 p.p.m. it is usually preferable to convert about 9099 percent of the organic nitrogen in the upper catalyst bed comprising the conventional, nonzeolitic catalyst and utilize the zeolite-based catalyst B in the lower bed to complete the desired denitrogenation. If the feedstock contains only about 100-200 p.p.m. of organic nitrogen and it is desired to reduce the nitrogen content to about 2 p.p.m., it is generally preferable to convert only about 50-80 percent of the organic nitrogen in the upper catalyst bed. It is generally advantageous to utilize the conventional, nonzeolitic catalyst to convert the less resistant organic nitrogen compounds, mainly the monocyclic and bicyclic compounds, and to utilize the zeolite-based hydrofining catalyst to convert the high-boiling, more resistant, organic nitrogen compounds having three or more rings, e.g., the carbazoles. Accordingly, it is preferable to effect relatively more denitrogenation in the lower bed containing the zeolite-based catalyst B where a large proportion, e.g.,

All-- 30 percent, of the organic nitrogen compounds are the highly resistant compounds than where only a small proportion, e.g., 5 percent, of the nitrogen compounds are the highly resistant compounds.

In broad summary, it may be said that as a general rule the degree of denitrogenation effected in the nonzeolitic catalyst A should be sufiicient to reduce the organic nitrogen content of the feed to between about 5 and 250, preferably between about 20l50, p.p.m., for at these organic nitrogen levels the zeolite-based catalyst B appears to exhibit its optimum selective denitrogenation activity.

The process conditions in each of the catalyst beds A and B are suitably adjusted to effect the above specified nitrogen removal in each of the beds. It is usually desirable to maintain both of the catalyst beds at substantially the same temperature, pressure and l-l loil ratio, and to vary the respective space velocities over each bed to effect the desired nitrogen removal by each of the respective catalysts. Accordingly, the space velocity with respect to catalyst B is generally 2-20 times, and preferably about 4-8 times, the space velocity with respect to catalyst A. The overall space velocity with respect to both catalysts is preferably between about 0.7 and 5.

HYDROFINING CATALYSTS As stated hereinabove, the catalyst in the upper bed A of hydrofiner 8 may comprise any of the conventional, substantially nonzeolitic, hydrofining catalysts. the base preferably having an ion exchange capacity of less than about 0.5 meq./g. Suitable catalysts include but are not limited to the transitional metals and sulfides thereof, and especially a Group VIII metal and/or sulfide (particularly cobalt or nickel) and/or a Group VI-B metal and/or sulfide (preferably molybdenum or tungsten). Such catalysts preferably are supported on an amorphous, nonzeolitic base in proportions ranging between about 2 percent and 25 percent by weight. Suitable bases include in general the difficulty reducible inorganic oxides which are amorphous and essentially nonzeolitic, e.g., alumina, silica, zirconia, titania, and clays such as montmorillonite, bentonite, etc. Preferably the base should display little or no cracking activity, and hence bases having a cracking activity greater than that corresponding to a Cat-A Activity Index of about 25 are to be avoided. The preferred base is activated alumina, and especially activated alumina containing about 3-15 percent by weight of coprecipitated silica-gel. The preferred hydrofining catalysts consist of nickel sulfide plus molybdenum sulfide supported on silica-stabilized alumina. Compositions containing between about 1 percent and 5 percent of Ni, 3 percent and 20 percent of Mo, 3 percent and 15 percent of SiO and the balance A1 0 and wherein the atomic ratio of Ni/Mo is between about 0.2 and 4 are specifically contemplated.

Catalyst B in the lower portion of hydrofiner 8 comprises a minor proportion of at least one transitional metal hydrogenating component, preferably a Group Vl-B metal and/or sulfide (preferably 5 to 30 percent molybdenum or tungsten) and/or a Group VIII metal and/or sulfide (preferably l-l0 percent of nickel or cobalt or 0.05 to 3 percent of palladium or platinum). The hydrogenating component is supported on a cracking base comprised of a zeolitic aluminosilicate, preferably a zeolite having relatively uniform crystal pore diameters of about 6-14 A., wherein the zeolitic cations comprise mainly hydrogen ions and/or polyvalent metal ions. These zeolites may be used as the sole base, or they may be mixed with a minor proportion of one or more of the nonzeolitic bases such as silica-alumina cogel. Suitable zeolites include for example those of the X, Y, or L crystal types, mordenite, chabazite, and the like. Either crystalline and/or noncrystalline, amorphous zeolitic gases may be employed. In the case of both the crystalline and the noncrystalline bases, it is preferred that the ion exchange capacities thereof be greater than about 1 .0 meq./g.

Hilllll As stated hereinabove, contrary to the present thinking in the art, it is desirable that the zeolitic base have a cracking activity greater than that corresponding to a Cat-A Activity Index of 40, and preferably greater than about 50. The Cat-A Activity Index of a catalyst is numerically equal to the volume-percent of gasoline produced in the standard Cat-A activity test as described in National Petroleum News, Aug. 2, 1944, vol. 36, p. R-537.

A particularly active and useful class of zeolite bases are those having a relatively high SiO /Al O mole ratio, e.g., between about 3 and 10. The preferred zeolitesare those having crystal pore diameters between about 8-12 A., and wherein the SiO /Al 0 mole ratio is between about 3 and 6. A prime example of a zeolite falling in this preferred group is thesynthetic Y molecular sieve.

The naturally occurring zeolites are normally found in a sodium form, an alkaline earth metal form, ormixed forms The synthetic zeolites normally are prepared in the sodium form. In any case it is preferred that most or all of the original zeolitic monovalent metals be ion-exchanged out with a polyvalent metal, or with an ammonium salt followed by heating to decompose the zeolitic ammonium ions, leaving intheir place hydrogen ions and/or exchange sites which have actually been decationized by further removal of water:

Both the hydrogen zeolites and the decationized zeolites possess desirable catalytic activity. Both of these forms, and the mixed forms, are designated herein as being metal-cation-deficient." Hydrogen or decationized Y-sieve zeolites are more particularly described in US. Pat. No. 3,130,006.

Mixed polyvalent metal-hydrogen zeolites may be prepared by ion exchanging first with an ammonium salt, then partially back exchanging with a polyvalent metal salt, and then calcining. Suitable polyvalent metal cations include the divalent metals such as magnesium, calcium, zinc, cobalt, nickel, manganese and the like; the rare earth metals, e.g., cerium, or in general any of the polyvalent metals of Group [-8 through Group VIII.

The hydrogenated metal, e.g., molybdenum, nickel, platinum and/or palladium is then added to the base. The metal may be deposited on the zeolitic type cracking base by ion exchange. This can be accomplished by digesting the zeolite with an aqueous solution ofa suitable compound of the desired metal as described for example in US. Pat. No. 3,236,762.

Following the above procedures, the zeolite may be mixed with one or more of the nonzeolitic amorphous gels such as alumina and/or silica-alumina, then pelleted and calcined at temperatures between about 600-l,200 F. The resulting catalyst is then presulfided if desired.

HYDROCRACKING CATALYSTS The hydrocracking catalysts employed herein comprise a transitional metal hydrogenating component such as a Group VI B and/or a Group VIII metal and/or sulfides thereof im-' pregnated on solid cracking base having a high cracking activity, preferably those having a cracking activity greater than that corresponding to a Cat-A Activity Index of 50. Examples of suitable hydrocracking bases are active cogel composites of silica-alumina, silicamagnesia, silicazirconia, aluminaboria, acid-treated clays, acidic metal phosphates and crystalline or noncrystalline aluminosilicate zeolites. The preferred hydrocracking catalysts are the zeolite-based compositions conforming to the above description of hydrofining catalyst B, or corresponding zeolite-based compositions wherein palladium or platinum is the hydrogenating metal. The novel hydrofining process described herein is especially useful where the hydrocracking catalyst is highly sensitive to organic nitrogen poisoning.

FEEDSTOCKS Feedstocks which may be employed herein include in general any mineral oil fraction boiling at least partly above the boiling rangeof the desired product. For gasoline, jet fuel, LPG, light gas oil or distillate production, the primary feedstockscomprise straight run gas oils, coker distillate gas oils, and/or cycle oils derived from catalytic or thermal cracking operations and the like. Deasphalted crude oils, shale oils, tar sand oils, and the like are also included. The feedstocks generally utilized have end boiling points between about 700 F. and l,300 F. and contain up to about 2 percent by weight of nitrogen. The invention is particularly useful in the denitrogenation of high-boiling feedstocks which contain highly resistant organic nitrogen compounds such as the carbazoles and the like which are difficult if not impossible to remove by utilizing a conventional nonzeolitic hydrofining catalyst at conventional process conditions. The invention is most useful where the feedstock has an end boiling point above 850 F. and wherein at least about 10 percent of the feedstock boils above 800 F.

The particularly novel feature of the invention is the discovery that a catalyst comprised of a hydrogenating metal deposited on an active zeolitic base can be employed in combination with a conventional, nonzeolitic, hydrofining catalyst in a manner such as to reduce the organic nitrogen content of a mineral oil fraction to low levels at relatively high overall space velocities and at relatively low temperatures and presssures. Specifically, it has been found that the novel dualcatalyst system is more efficient than single-catalyst systems comprising either conventional, nonzeolitic hydrofining catalysts or a zeolite-based catalyst, for reducing the organic nitrogen content of heavy feedstocks to low levels. This will be apparent from the specific examples which follow.

EXAMPLE I This example illustrates that, by using. the dual-catalyst system of this invention, the nitrogen content of a high-boiling feedstock containing 2,000 p.p.m. nitrogen can be reduced to 9.4 p.p.m. at a temperature of about 725 F., pressure of about 1,500 p.s.i.g. and at a combined liquid hourly space velocity of about 1.0. The example further illustrates that the dualcatalyst system is more efficient than the single-catalyst systemusing a conventional nonzeolitic catalyst.

A feedstock, having a gravity of 226 APl, a boiling range of 443-883 F., a percent boiling point of 805 F., and containing 2,000 p.p.m. nitrogen was first contacted with a conventional, non-zeolitic, hydrofining catalyst comprised of l/l6-inch extrudate of a presulfided composite of about l5 percent molybdenum oxide and 3 percent nickel oxide supported on an alumina carrier stabilized by-the addition of 5 percent silica. The total effluent was thereafter contacted with a zeolite-based hydrofining catalyst comprising l/ l 6-inch extrudate of a presulfided composite of about 0.5 percent palladium supported on a magnesium=hydrogen Y zeolite cracking base having a cracking activity higher than that corresponding to a Cat-A Activity Index of 50, and which was mixed with about 20 percent alumina. The zeolite base comprised about 3 weight-percent zeolitic magnesium as MgO,

. and about 1 weight-percent sodium as Na- O, the remaining zeolitic cations being hydrogen ions. The process conditions over the respective catalysts were:

The product contained about 9.4 p.p.m. of organic nitrogen.

The pseudo first-order rate constant K expressed by the equation K=LHSV 1n (N,/N,,), where N, is the initial feed nitrogen content and N, is the product nitrogen content, was 5 calculated to be 5.4. The effluent from catalyst A contained 48 p.p.m. of nitrogen. The rate constant for conversion in the upper bed comprising catalyst A is thus 4.7, and the rate constant for conversion in the lower bed comprising catalyst B is 8.2.

The same feedstock was contacted with the conventional nonzeolitic hydrofining catalyst A at a temperature of 718 F., a pressure of 1,500 p.s.i.g., a H /oil ratio of 6,000 SCF/B and at a space velocity of 1.0. The nitrogen content of the effluent was 34.0. The rate constant was calculated to be 4.1 which, after correction for temperature difference, compares unfavorably with the 5.4 rate constant when the dual-catalyst system was utilized at a combined average bed temperature of about 725 F., 1,500 p.s.i.g. and at 1.0 space velocity.

EXAMPLE II This example further illustrates that the dual-catalyst system utilizing both the nonzeolite based catalyst and the zeolitebased catalyst is much more efficient than the single-catalyst system which employs only the conventional nonzeolitic catalyst.

A feedstock having a gravity of3 l.1 API, a boiling range of 523-999 F., and containing 1,230 p.p.m. nitrogen was first contacted with a conventional, nonzeolitic, hydrofining catalyst comprised of a presulfided composite of molybdenum oxide supported on an alumina carrier stabilized by the addition of silica. The total effluent was thereafter contacted with the zeolite-based hydrofining catalyst comprising 1] 16-inch extrudate of a presulfided composite of about 0.5 percent palladium supported on a magnesium-hydrogen Y zeolite cracking base substantially identical to that employed in Example l. The process conditions over the respective catalysts The effluent contained 2 p.p.m. of organic nitrogen. The firstorder rate constant for conversion in the dual-catalyst system was calculated to be 5.0. The nitrogen content of the effluent from catalyst A was p.p.m. The rate constant for conversion in the upper bed comprising catalyst A was 3.5 and the rate constant for conversion in the lower bed comprising catalyst B was 7.9.

The same feedstock was contacted with only the nonzeolitic catalyst A at the same process conditions except at the space velocity of 0.7 which is a lower space velocity than the 0.78 overall space velocity in the above experiment. The effluent contained 34 p.p.m. of organic nitrogen. The first-order rate constant conversion in the single-bed comprising nonzeolitic catalyst A was calculated to be 2.5 which compares unfavorably with the 5.0 rate constant for conversion in the dualcatalyst system.

EXAMPLE III This example illustrates that the zeolite-based catalyst used alone for high-nitrogen feeds is not as effective as the dualcatalyst system.

The feedstock of Example I, which contained 2,000 p.p.m. of nitrogen, was contacted with a zeolite-based catalyst comprising a presulfided composite of 15 percent molybdenum oxide and 5 percent nickel oxide on a cobalt-stabilized hydrogen Y zeolite (a catalyst which has been found to have a higher denitrogenation activity than the palladium zeolite catalyst employed in Example I) at 740 F., 1,000 p.s.i.g., 6,000 SCF/B, and at a LHSV of 1.0. The nitrogen content of the product was 69 p.p.m. The first-order rate constant was calculated to be 3.4 which, after correction for temperature and pressure differences, compares unfavorably with the 5.4 rate constant of Example I wherein the dual-catalyst system was employed.

The following table summarizes the results of the foregoing examples:

Several observations are evident from the foregoing results:

1. The dual-catalyst hydrofining system is capable of reducing the nitrogen content of an 883 F. end point gas oil feedstock from about 2,000 p.p.m. to the low level of 9.4 p.p.m. at the process conditions of 725 F., 1,500 p.s.i.g. and at the relatively high space velocity of 1.0 and is capable of reducing the nitrogen content of a 999 F. end point feedstock to 2.0 p.p.m. at the process conditions of 785 F., 2,500 p.s.i.g. and at the relatively high space velocity of 0.78.

2. The novel dual-catalyst hydrofining system is far more efficient for reducing the organic nitrogen content of a feedstock than is a single-catalyst hydrofining system comprising only a conventional, nonzeolitic hydrofining catalyst.

3. The dual-catalyst system is more efficient for reducing the nitrogen content of high-nitrogen gas oil feedstocks than is a hydrofining system comprising only a zeolite-based catalyst.

Results substantially similar to those described in the above examples are obtained when other feedstocks and catalysts within the purview of this invention are substituted therein. It is not intended that the invention be limited to nonessential details described herein, since many variations may be made by those skilled in the art without departing from the scope or spirit of the following claims.

We claim:

1. A hydrofining process for reducing the organonitrogen content of a mineral oil feedstock containing substantial amounts of organonitrogen compounds which comprises:

1. contacting said feedstock with a first catalyst comprising a transitional metal hydrogenation component selected from the class consisting of the Group Vl-B and Group VIII metals and their oxides and sulfides supported on an amorphous, substantially nonzeolitic base having a cracking activity less than that corresponding to a Cat-A activity index of about 25 under hydrofining conditions of temperature, pressure and liquid hourly space velocity and in the presence of about 0.5 to about 20 MSCF of hydrogen per barrel of said feedstock and substantially reducing the organonitrogen content of said feedstock to produce an intermediate hydrocarbon product containing a substantial although markedly lower amount of organonitrogen compounds;

2. contacting said intermediate product from step one with a second catalyst comprising a transitional metal hydrogenation component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and a zeolitic aluminosilicate having a cracking activity greater than that corresponding a Cat-A activity index of about 40 under hydrofining conditions of temperature, pressure and liquid hourly space velocity in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said intermediate product and further substantially reducing the organonitrogen content of said intermediate product in the presence of less than about 25 volume percent conversion to lower boiling products.

2. The method of claim 1 wherein said organonitrogen content of said mineral oil feedstock is reduced by about 50 to about 99 percent in the presence of said first catalyst of step (1), said organonitrogen content of said intermediate product is reduced to less than 25 p.p.m. in the presence of said second catalyst of step (2) in the presence of less than about 15 volume percent conversion to gasoline range hydrocarbons.

3. The method of claim 1 wherein said mineral oil feedstock comprises at least about 100 p.p.m. of organonitrogen compounds, said feedstock is contacted in step (1) under conditions sufficient to convert about 50 to about 99 percent of said organonitrogen compounds and said intermediate product is contacted in step (2) under conditions sufficient to reduce the organonitrogen content to less than about 25 p.p.m. at a liquid hourly space velocity greater than the liquid hourly space velocity ofstep (l).

4. The method of claim 1 wherein said mineral oil feedstock comprises at least about 100 p.p.m. of organonitrogen compounds and is contacted in step (I) at a temperature of about 600 to about 850 F. at a pressure of about 400 to about 4,000 p.s.i.g. at a liquid hourly space velocity of about 0.5 to about in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said feedstock at a first liquid hourly space velocity sufficient to convert about 50 to about 99 percent of said organonitrogen compounds and said intermediate product is contacted in step (2) at a temperature of about 600 to about 850 F. and a pressure of about 400 to about 4,000 p.s.i.g. in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said intermediate product at a second liquid hourly space velocity about 2 to about 20 times greater than said first space velocity sufficient to further substantially reduce the organonitrogen content of said intermediate feedstock in the presence of less than about volume percent conversion to gasoline range hydrocarbons.

5. The method of claim I wherein the hydrogenating component in said second catalyst is selected from the Group VIII noble metals and the oxides and sulfides thereof and the zeolitic cation equivalents of said second catalyst comprise hydrogen ions or polyvalent metal ions.

6. The method of claim 1 wherein said second catalyst is essentially palladium supported on a hydrogen form of Y-zeolite and said first catalyst comprises molybdenum supported on base comprising primarily alumina.

7. The method of claim 1 which further comprises passing at least the hydrocarbon effluent from step (2) into contact with a third catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII Metals and their oxides and sulfides and a solid cracking base having a cracking activity greater than that corresponding to a Cat-A activity index of about 50 under hydrocracking conditions of temperature, pressure and liquid hourly space velocity in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon sufficient to convert a substantial proportion of said hydrocarbon to lower boiling hydrocarbons.

8. The method of claim 7 wherein said hydrocarbons are hydrocracked at a temperature of about 550 to about 850 F.

at a pressure of about 400 to about 3,000 p.s.i.g. at a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said hydrocarbon.

9. The method of hydrofining hydrocarbons containing a substantial proportion of organonitrogen compounds to reduce the concentration of said organonitrogen compounds which comprises 1. contacting said hydrocarbon in the presence of a first catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and an amorphous substantially nonzeolitic base having a cracking activity less than that corresponding to a Cat-A activity index of about 25 under hydrofining conditions of temperature, pressure and liquid hourly space velocity in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon sufficient to convert about 50 to about 99 percent of said organonitrogen compounds;

2. contacting at least the hydrocarbon effluent from step 1) containing a substantial although markedly reduced concentration of organonitrogen compounds with a second catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and at least one zeolitic aluminosilicate having a cracking activity greater than that corresponding to a Cat-A activity index of about 40 under hydrofining conditions of temperature, pressure and at a liquid hourly space velocity greater than the liquid hourly space velocity at which said hydrocarbon is contacted in step (I) in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon sufficient to further substantially reduce the organonitrogen content of said hydrocarbon to a level below about 25 p.p.m. and less than about 25 volume percent conversion of said hydrocarbons to lower boiling hydrocarbons.

10. The method of claim 9 wherein said hydrocarbon is contacted in step (I) at a temperature of about 600 to about 850 F., a pressure of about 400 to about 4,000 p.s.i.g., a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said hydrocarbon sufficient to convert about 50 to about 99 percent of said organonitrogen compounds and reduce the organonitrogen compound concentration in said hydrocarbon to a level of about 5 to about 250 p.p.m. nitrogen and said hydrocarbon product from step (I) is contacted in step (2) at a temperature of about 600 to about 850 F. and a pressure to about 400 in about 4,000 p.s.i.g. at a second liquid hourly space velocity in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said hydrocarbon, said second space velocity being about 2 to about 20 times greater than the space velocity in which said feed is contacted in step (1) sufficient toreduce the organonitrogen content of said hydrocarbon to less than 25 p.p.m.

11. The method of claim 10 wherein said hydrofining conditions in step (2) are sufficient to reduce the organonitrogen content of said-hydrocarbon to less than about 25 p.p.m. in the absence of more than 15 volume percent conversion of said hydrocarbon to gasoline range hydrocarbons.

12. The method of claim 9 wherein the hydrogenation metal in said second catalyst is a Group VIII noble metal and the zeolitic cation equivalents of said second catalyst comprise at least one of hydrogen ions and polyvalent metal cations, said hydrocarbon is contacted in step (I) under conditions sufficient to reduce the organonitrogen content thereof to about 5 to about 250 ppm. and said hydrocarbon product from step (1) is contacted in step (2) under hydrofining conditions sufficient to reduce the organonitrogen content thereof to less than about 25 p.p.m. at a liquid hourly space velocity of about 2 to about 20 times greater than the liquid hourly space velocity of which said hydrocarbon is contacted in step (l in all r the presence of less than about volume percent conversion.

of hydrocarbon to gasoline range hydrocarbons.

13. The method of claim 9 wherein the hydrofined product from step (2) is contacted under hydrocracking conditions with a third catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and a cracking base having a cracking activity greater than that corresponding to a Cat-A activity index of about 50 in the presence of hydrogen and under hydrocracking conditions of temperature, pressure and liquid hourly space velocity sufficient to convert a substantial proportion of said hydrocarbons to lower boiling hydrocarbons.

14. The method of claim 13 wherein said hydrocarbon is contacted in the presence of said third catalyst at a temperature of about 550 to about 850 F. at a pressure of about 400 to about 3,000 p.s.i.g. at a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about MSCF hydrogen per barrel ofsaid hydrocarbon.

15. The method of converting hydrocarbons containing a substantial proportion of organonitrogen compounds which comprise 1. contacting a said hydrocarbon with a first catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and an amorphous base having a cracking activity less than that corresponding to a Cat-A activity index of about under hydrofining conditions of temperature and pressure at a first liquid hourly space velocity in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon sufficient to convert about 50 to about 99 percent of said organonitrogen compounds;

. contacting at least the hydrocarbon effluent from step (1) with a second catalyst comprising a transitional metal hydrogenating component selected from the class consisting of a Group VI-B and Group VIII metals and their oxides and sulfides and a zeolitic base having a cracking activity greater than that corresponding to a Cat-A activity index of about 40 under hydrofining conditions of temperature and a pressure at a second liquid hourly space velocity greater than said first liquid hourly space velocity in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon effluent sufficient to further substantially reduce the organonitrogen content of said hydrocarbon to a level of less than about 25 p.p.m. nitrogen in the absence of substantial hydrocracking corresponding to less than 25 percent conversion of said hydrocarbon to lower boiling hydrocarbons;

. contacting at least the hydrocarbon effluent from step (2) with a third catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and a solid cracking base under hydrocracking conditions of temperature, pressure and liquid hourly space velocity in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon sufficient to convert the substantial proportion of said hydrocarbons to lower boiling hydrocarbons.

16. The method of claim 15 wherein said hydrocarbon is contacted in step (1) under conditions sufficient to reduce the organonitrogen content thereof to a level of about 5 to about 250 p.p.m., said hydrocarbon effluent is contacted in step (2) at a liquid hourly space velocity about 2 to about 20 times greater than said first space velocity under hydrofining conditions sufficient to reduce the organonitrogen content of said hydrocarbon below about 25 p.p.m. in the presence of less than about 15 percent conversion to lower boiling hydrocarbons and said hydrocarbon effluent from step (2) is contacted under hydrocracking conditions under step (3) sufficient to convert about 20 to about 70 percent of said hydrocarbon to lower boiling products.

17. The method of claim 15 wherein said hydrocarbon is contacted in step (1) at a temperature of about 600 to about 850 F. at a pressure of about 400 to about 4,000 p.s.i.g. and a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF of hydrogen per barrel of said hydrocarbon sufficient to convert at about 50 to about 99 percent of said organonitrogen compounds and reduce the organonitrogen concentration of said hydrocarbon to about 5 to about 250 p.p.m., said hydrocarbon effluent from step (1) is contacted in step (2) in the presence of said second catalyst at a temperature of about 600 to about 850 F., a pressure of about 400 to about 4,000 p.s.i.g. at a second liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF of hydrogen per barrel of said hydrocarbon, said second liquid hourly space velocity being about 2 to about 20 times greater than said first liquid hourly space velocity, in said last hydrofining conditions being sufficient to further substantially reduce the organonitrogen content of said hydrocarbon to less than about 25 p.p.m. in the presence ofless than about 15 volume percent conversion of said hydrocarbon to lower boiling products and said hydrocarbon from step (2) is contacted under hydrocracking conditions in step (3) including a temperature of about 550 to about 850 F., a pressure of about 400 to about 3,000 p.s.i.g. at a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF of hydrogen per barrel of said hydrocarbon sufficient to convert about 20 to about 70 volume percent of said hydrocarbon to lower boiling products.

UNITED STATES PATENT OFFICE v QERTIFICATE OF CORRECTIOPI Patent NO. 3,644,197 Dated February 22. 1972 Inventor(s) Arnold E. Kelley, et. al.

It is certified that error appears in the above-identified patent and that said Letters Patentare hereby corrected as shown below:

Column 9, line 3, cancel "one" and insert l line 8, after "corresponding" insert to line 16, cancel "25" and insert l5 line 16, after "products" cancel the period and insert and continue with the following insertion: (3) withdrawing from said second zone a hydrocarbon product of reduced organonitrogen content. Column 10, line 38, cancel "2S" and insert l5 line 39, after "hydrocarbons" cancel the period and insert and continue with the following insertion: (3) withdrawing from said second zone a hydrocarbon product of reduced organonitrogen contenta Column 11, line 48, change "25" to read l5 after line 49,. insert the following (3) withdrawing vfrom said second zone a hydrocarbon product of reduced organonitrogen content; and line 50, change "3." to read 4.

Signed and sealed this 12th day of December 1972.

(SEAL) Atteflt:

EDWARD M. FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM po'wso (10-59) uscoMM-oc scan-Pas A [1.5. GOVERNMENT PRINTlNG OFFICE 2 [9 59 0-356-33, 

2. contacting said intermediate product from step one with a second catalyst comprising a transitional metal hydrogenation component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and a zeolitic aluminosilicate having a cracking activity greater than that corresponding a Cat-A activity index of about 40 under hydrofining conditions of temperature, pressure and liquid hourly space velocity in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said intermediate product and further substantially reducing the organonitrogen content of said intermediate product in the presence of less than about 25 volume percent conversion to lower boiling products.
 2. The method of claim 1 wherein said organonitrogen content of said mineral oil feedstock is reduced by about 50 to about 99 percent in the presence of said first catalyst of step (1), said organonitrogen content of said intermediate product is reduced to less than 25 p.p.m. in the presence of said second catalyst of step (2) in the presence of less than about 15 volume percent conversion to gasoline range hydrocarbons.
 2. contacting at least the hydrocarbon effluent from step (1) containing a substantial although markedly reduced concentration of organonitrogen compounds with a second catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and at least one zeolitic aluminosilicate having a cracking activity greater than that corresponding to a Cat-A activity index of about 40 under hydrofining conditions of temperature, pressure and at a liquid hourly space velocity greater than the liquid hourly space velocity at which said hydrocarbon is contacted in step (1) in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon sufficient to further substantially reduce the organonitrogen content of said hydrocarbon to a level below about 25 p.p.m. and less than about 25 volume percent conversion of said hydrocarbons to lower boiling hydrocarbons.
 2. contacting at least the hydrocarbon effluent from step (1) with a second catalyst comprising a transitional metal hydrogenating component selected from the class consisting of a Group VI-B and Group VIII metals and their oxides and sulfides and a zeolitic base having a cracking activity greater than that corresponding to a Cat-A activity index of about 40 under hydrofining conditions of temperature and a pressure at a second liquid hourly space velocity greater than said first liquid hourly space velocity in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon effluent sufficient to further substantially reduce the organonitrogen content of said hydrocarbon to a level of less than about 25 p.p.m. nitrogen in the absence of substantial hydrocracking corresponding to less than 25 percent conversion of said hydrocarbon to lower boiling hydrocarbons;
 3. contacting at least the hydrocarbon effluent from step (2) with a third catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and a solid cracking base under hydrocracking conditions of temperature, pressure and liquid hourly space velocity in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon sufficient to convert the substantial proportion of said hydrocarbons to lower boiling hydrocarbons.
 3. The method of claim 1 wherein said mineral oil feedstock comprises at least about 100 p.p.m. of organonitrogen compounds, said feedstock is contacted in step (1) under conditions sufficient to convert about 50 to about 99 percent of said organonitrogen compounds and said intermediate product is contacted in step (2) under conditions sufficient to reduce the organonitrogen content to less than about 25 p.p.m. at a liquid hourly space velocity greater than the liquid hourly space velocity of step (1).
 4. The method of claim 1 wherein said mineral oil feedstock comprises at least about 100 p.p.m. of organonitrogen compounds and is contacted in step (1) at a temperature of about 600* to about 850* F. at a pressure of about 400 to about 4,000 p.s.i.g. at a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said feedstock at a first liquid hourly space velocity sufficient to convert about 50 to about 99 percent of said organonitrogen compounds and said intermediate product is contacted in step (2) at a temperature of about 600* to about 850* F. and a pressure of about 400 to about 4,000 p.s.i.g. in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said intermediate product at a second liquid hourly space velocity about 2 to about 20 times greater than said first space velocity sufficient to further substantially reduce the organonitrogen content of said intermediate feedstock in the presence of less than about 15 volume percent conversion to gasoline range hydrocarbons.
 5. The method of claim 1 wherein the hydrogenating component in said second catalyst is selected from the Group VIII noble metals and the oxides and sulfides thereof and the zeolitic cation equivalents of said second catalyst comprise hydrogen ions or polyvalent metal ions.
 6. The method of claim 1 wherein said second catalyst is essentially palladium supported on a hydrogen form of Y-zeolite and said first catalyst comprises molybdenum supported on a base comprising primarily alumina.
 7. The method of claim 1 which further comprises passing at least the hydrocarbon effluent from step (2) into contact with a third catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII Metals and their oxides and sulfides and a solid cracking base having a cracking activity greater than that corresponding to a Cat-A activity index of about 50 under hydrocracking conditions of temperature, pressure and liquid hourly space velocity in the presence of at least about 0.5 MSCF hydrogen per barrel of said hydrocarbon sufficient to convert a substantial proportion of said hydrocarbon to lower boiling hydrocarbons.
 8. The method of claim 7 wherein said hydrocarbons are hydrocracked at a temperature of about 550* to about 850* F. at a pressure of about 400 to about 3,000 p.s.i.g. at a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said hydrocarbon.
 9. The method of hydrofining hydrocarbons containing a substantial proportion of organonitrogen compounds to reduce the concentration of said organonitrogen compounds which comprises
 10. The method of claim 9 wherein said hydrocarbon is contacted in step (1) at a temperature of about 600* to about 850* F., a pressure of about 400 to about 4,000 p.s.i.g., a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said hydrocarbon sufficient to convert about 50 to about 99 percent of said organonitrogen compounds and reduce the organonitrogen compound concentration in said hydrocarbon to a level of about 5 to about 250 p.p.m. nitrogen and said hydrocarbon product from step (1) is contacted in step (2) at a temperature of about 600* to about 850* F. and a pressure to about 400 in about 4,000 p.s.i.g. at a second liquid hourly space velocity in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said hydrocarbon, said second space velocity being about 2 to about 20 times greater than the space velocity in which said feed is contacted in step (1) sufficient to reduce the organonitrogen content of said hydrocarbon to less than 25 p.p.m.
 11. The method of claim 10 wherein said hydrofining conditions in step (2) are sufficient to reduce the organonitrogen content of said hydrocarbon to less than about 25 p.p.m. in the absence of more than 15 volume percent conversion of said hydrocarbon to gasoline range hydrocarbons.
 12. The method of claim 9 wherein the hydrogenation metal in said second catalyst is a Group VIII noble metal and the zeolitic cation equivalents of said second catalyst comprise at least one of hydrogen ions and polyvalent metal cations, said hydrocarbon is contacted in step (1) under conditions sufficient to reduce the organonitrogen content thereof to about 5 to about 250 p.p.m. and said hydrocarbon product from step (1) is contacted in step (2) under hydrofining conditions sufficient to reduce the organonitrogen content thereof to less than about 25 p.p.m. at a liquid hourly space velocity of about 2 to about 20 times greater than the liquid hourly space velocity of which said hydrocarbon is contacted in step (1) in the presence of less than about 15 volume percent conversion of hydrocarbon to gasoline range hydrocarbons.
 13. The method of claim 9 wherein the hydrofined product from step (2) is contacted under hydrocracking conditions with a third catalyst comprising a transitional metal hydrogenating component selected from the class consisting of the Group VI-B and Group VIII metals and their oxides and sulfides and a cracking base having a cracking activity greater than that corresponding to a Cat-A activity index of about 50 in the presence of hydrogen and under hydrocracking conditions of temperature, pressure and liquid hourly space velocity sufficient to convert a substantial proportion of said hydrocarbons to lower boiling hydrocarbons.
 14. The method of claim 13 wherein said hydrocarbon is contacted in the presence of said third catalyst at a temperature of about 550* to about 850* F. at a pressure of about 400 to aboUt 3,000 p.s.i.g. at a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF hydrogen per barrel of said hydrocarbon.
 15. The method of converting hydrocarbons containing a substantial proportion of organonitrogen compounds which comprise
 16. The method of claim 15 wherein said hydrocarbon is contacted in step (1) under conditions sufficient to reduce the organonitrogen content thereof to a level of about 5 to about 250 p.p.m., said hydrocarbon effluent is contacted in step (2) at a liquid hourly space velocity about 2 to about 20 times greater than said first space velocity under hydrofining conditions sufficient to reduce the organonitrogen content of said hydrocarbon below about 25 p.p.m. in the presence of less than about 15 percent conversion to lower boiling hydrocarbons and said hydrocarbon effluent from step (2) is contacted under hydrocracking conditions under step (3) sufficient to convert about 20 to about 70 percent of said hydrocarbon to lower boiling products.
 17. The method of claim 15 wherein said hydrocarbon is contacted in step (1) at a temperature of about 600* to about 850* F. at a pressure of about 400 to about 4,000 p.s.i.g. and a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF of hydrogen per barrel of said hydrocarbon sufficient to convert at about 50 to about 99 percent of said organonitrogen compounds and reduce the organonitrogen concentration of said hydrocarbon to about 5 to about 250 p.p.m., said hydrocarbon effluent from step (1) is contacted in step (2) in the presence of said second catalyst at a temperature oF about 600* to about 850* F., a pressure of about 400 to about 4,000 p.s.i.g. at a second liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF of hydrogen per barrel of said hydrocarbon, said second liquid hourly space velocity being about 2 to about 20 times greater than said first liquid hourly space velocity, in said last hydrofining conditions being sufficient to further substantially reduce the organonitrogen content of said hydrocarbon to less than about 25 p.p.m. in the presence of less than about 15 volume percent conversion of said hydrocarbon to lower boiling products and said hydrocarbon from step (2) is contacted under hydrocracking conditions in step (3) including a temperature of about 550* to about 850* F., a pressure of about 400 to about 3, 000 p.s.i.g. at a liquid hourly space velocity of about 0.5 to about 10 in the presence of about 0.5 to about 20 MSCF of hydrogen per barrel of said hydrocarbon sufficient to convert about 20 to about 70 volume percent of said hydrocarbon to lower boiling products. 